The present invention relates to cutting tools which are typically used in metal working applications such as turning lathes, milling machines, turret lathes, and similar machine tools. More particularly, the present invention relates to a new and improved cutting insert, i.e. a cutting tool or element which is fixed in the recess of a tool holder and formed with several cutting edges which can be brought successively into cutting position by adjustment of the insert relative to the recess of the tool holder. Typically, the insert is formed from a block of an abrasion resistant material, such as a cemented carbide or the like, and is fixed to the tool holder by a clamp means or pin member received through a central aperture in the insert. The insert is easily indexable by virtue of the fact that the clamp or pin member may be released and the insert rotated so as to place a new cutting edge into an operative position. In operation, a metal workpiece is selectively brought into contact with the cutting edge of the insert whereby continuous strand portions of the metal workpiece, commonly referred to as chips, are removed in order to form the desired configuration on the workpiece. An important consideration in the machining process is the control of the continuous metal strands or chips as they are being removed from the workpiece. It will be appreciated that at the high speed at which machining is done today the uncontrolled flow of the metal strands, which have sharp edges, would present a very serious safety hazard to the tool operator. In addition, if the chip flow were not controlled, it would be very likely that the chip would contact and damage the unused cutting edges of the insert, thus resulting in a shorter tool life.
Accordingly, known cutting tools typically include means for mechanically bending the snaking chip as it comes from the workpiece so as to break it into small individual chips that fall harmlessly to the floor before endangering the operator, and not interfere with the cutting edges of the insert nor the workpiece. One such means includes a member which is separate and distinct from the insert, and commonly referred to as a chip breaker. Typically, the chip braker is fixed to the tool holder and disposed directly above the insert so as to contact the chip strands as they are being removed from the workpiece, thus breaking the chip strands into smaller particles. The chip breaker also typically includes a sloped edge portion which guides the broken chips away from the cutting edge of the insert.
Another such means is actually integral with the insert itself. More particularly, the insert includes a built-in chip control groove which deflects the chips and forms the chips into an acceptable configuration. Several chip groove configurations are known and numerous attempts are continually made to improve the performance thereof.
One shortcoming of the prior art chip groove configurations is that they were of use of only limited applications. More specifically, the chip grooves and outer land areas provided on each insert were designed for particular feed rates, and particular machining depths (chip load). Therefore, it would be desirable to provide an indexable insert having a new and improved chip groove and land area configuration which enables the insert to be utilized throughout a broad range of feed rates, and under various chip loads.
In addition to feed rates and depth of cut, the indexable insert must be designed to perform in various situations wherein the power and force required in the machining application varied. As the force and power increase, temperatures also increase, which results in a higher incidence of thermal wear of the insert. Further, at higher temperatures, the chip strands themselves become more difficult to break, and the increased power tends to force the unbroken chips against the surface of the insert causing early tool failure. Therefore, it would be desirable to provide a new and improved indexable insert which is operative to reduce cutting forces in a given machining situation, thereby reducing temperatures and increasing the life of the insert.
Accordingly, it is an object of the subject invention to provide a new and improved cutting insert which includes a unique chip groove and land area configuration which may be utilized to machine cuts of various depths and at various feed rates.
It is a further object of the subject invention to provide a new and improved cutting insert including a unique chip groove configuration which provides greater chip control and reduces the force and power requirements for a given application thereby increasing metal removal rate per unit of power, and reducing temperature so as to minimize thermal wear and other heat associated problem.
It is another object of the subject invention to provide a new and improved cutting insert which includes positive back and side rake angles to further reduce force requirements thereby decreasing deflection as well as unwanted chatter and vibration, which affect the quality of machining as well as tool life.